When Local 1181 of the Amalgamated Transit Union sent its school-bus drivers and matrons out on strike, it claimed to be protecting their jobs.

Now that the strike has collapsed, we wonder whether those workers still think the union was, in fact, doing that.

In particular, we wonder about the more than 100 matrons who thought the end of the strike meant a return to their jobs — only to learn that they no longer had them.

Joseph Fazzia, owner of Canal Escorts in Red Hook, informed these workers that he was shutting down his company because the work stoppage had cost him hundreds of thousands of dollars in lost income.

As a result, these women lost their jobs.

Fazzia, who runs two other bus companies, invited the workers to apply to one of those. That will require them to join Teamsters Local 854, which didn’t strike. But even if they switch, there’s no guarantee they will ever get their jobs back.

This should be especially embarrassing for the ATU. The union was demanding that the city require the bus companies to include guaranteed, seniority-based job security in upcoming contract negotiations. Unfortunately for the workers, the courts made clear that the city was not legally bound to make such a requirement.

Some may think the matrons got what they deserved. Our view is that there’s no room for gloating. The real story here is that, once again, workers have been harmed by the bad judgment of a union that claims to represent their best interests.

For private-sector unions, the whole incident underscores an obvious truth that is too often ignored: At the end of the day, businesses have bottom lines they have to meet if they are to remain going concerns. Workers have a stake in their company meeting that bottom line, because if they can’t, the company will shut down and the workers will lose their jobs.

Just ask those 100 unfortunate bus matrons, who are now looking for other work because an unwise job action their union initiated on the grounds that it would give them greater job security has instead ended up taking away the jobs they had.